php中两个数组的差异，一个是键，另一个没有

$a = array("a","b"); 
$b = array("a"=>"one", "b" => "two","c"=>"three");

I need help in finding the difference between two arrays one with key and another without key.

required output

"c"=>"three"

Use array_diff_key() and array_flip():

$difference = array_diff_key(
    $b,
    array_flip($a)
);

For reference, see:

• http://php.net/manual/en/function.array-diff-key.php
• http://php.net/manual/en/function.array-flip.php

For an example, see:

• https://3v4l.org/YgNhB

Every array has keys. Even if you have not set them.

So, your arrays look like this:

$a = array(0=>"a",1=>"b"); 
$b = array("a"=>"one", "b" => "two","c"=>"three");

And you trying to compare the values of one array with the keys of the other.

That's why localheinz is using array_flip() in his answer.